This invention relates to an automatic paper feed device which supplies cutforms and other media automatically to terminal devices such as printers.
A device to automatically supply media to terminal devices such as printers was disclosed in Japanese Patent Application Laid-open No. 218238/1985. When different sized media are supplied with this type of device, there are conventionally different hoppers or paper cassettes for each size of media. Media are stored in and supplied from these hoppers.
The following is an explanation of the conventional automatic paper feed device based on the drawings. FIG. 1 is a partially cut-away side view showing the conventional paper feed device.
Media 2 is stacked and stored in hopper or cassette 3, which is installed in automatic paper feed device 1. Printer 4 is placed on top of automatic paper feed device 1. Supply roller 5 is installed above cassette 3 and feed roller 6 is also disposed inside the device. Moreover, spring 7 is provided underneath media 2, cassette container 9 is installed to the side of automatic paper feed device 1 and printer 4. Cassette container 9 contains cassettes 8 which store specific sizes of media which are not in use.
The operation of the conventional automatic paper feed device will be explained next. The media 2 which is stacked and stored in cassette 3 is pushed by spring 7 into contact with supply roller 5. Supply roller 5 is rotated in the direction of arrow G by a drive means not shown, and this causes the media to begin to be fed from the top, one sheet at a time. Media 2, which has begun to be fed, is sent to printer 4 by feed roller 6.
When one wishes to print media which is different in size from media 2 (stacked and stored in cassette 3) with printer 4, one takes cassette 3 out of automatic paper feed device 1. Cassette 8, in which is stored the media of the size desired, is then taken out of cassette container 9 and installed in automatic paper feed device 1. Paper feed to printer 4 may then be performed. Cassette 3, which has been taken out of automatic paper feed device 1 is then stored in cassette container 9. By manual input instructions are sent to printer 4 concerning the size of the media newly installed in automatic paper feed device 1.
However, different cassettes for respective sizes of media are necessary in devices constructed as above. Also, since the automatic paper feed device permits mounting of only one cassette a separate place or container for the multiple cassettes storing media not in use are needed. Because of this, cassettes not being used must be placed in the immediate vicinity of the automatic paper feed device and the amount of space needed for the installation of the device is a problem.
The automatic paper feed device described above also has the fault of requiring a number of cassettes in which specific sizes of media are stored. Because of this cassette container must be provided and this increases the number of structural parts, and raises the price of the automatic paper feed device.
Furthermore, because the operator must send instructions to the printer concerning the size of the media it is easy for errors to occur. When errors occur it is necessary to reprint, and this is a problem because media is wasted.
Another problem associated with the prior art is that the media is pushed against the hopping roller and paper feed is accomplished by the same coil springs always pushing up the media load plate. But because the weight of the media stored in the paper cassette varies according to its size, the pressure by which the top of the media is pushed against the hopping roller varies.
Therefore too great a pressure will be obtained when feeding smaller media if springs whose pressure is appropriate to larger media are used. This will increase the occurrence of multiple feeding, in which 2 or 3 sheets are fed at the same time. When springs appropriate to smaller media are used, the pressure obtained will be too little for larger media and feed misses, in which the media is not fed, will occur more often.